湘南地区沉积构造环境的地球化学探讨

根据湘南地区出露地层的岩石化学成分特征初步讨论了湘南地区的沉积构造环境。湘南地区细碎屑岩的ｗ（Ａｌ２Ｏ３）／ｗ（ＣａＯ＋Ｎａ２Ｏ），ｗ（Ｋ２Ｏ）／ｗ（Ｎａ２Ｏ）比值比较高，ｗ（Ａｌ２Ｏ３）／ｗ（ＳｉＯ２）比值比较低，与被动大陆边缘特征类似，各时代地层中硅质岩和页岩的ｗ（ＭｎＯ）／ｗ（ＴｉＯ２）比值为０．０２￣０．３，反映其沉积环境为浅海陆架环境，但下二叠统硅质岩中ｗ（ＭｎＯ）／ｗ（ＴｉＯ２）比值达

GEOCHEMICAL STUDY OF DEPOSITIONALTECTONIC SETTINGS OF SOUTHERN HUNANPROBVINCE

The depositional tectonic settingsof the sedimentary cover(from Sinian toJurassic)have been studiedin southernHunan.With the exception oftherocks in Permian Period,thew (Al2O3)/w(CaO+Na2O)and w(Na2O)ratios are higher,and w(Al2O3)/w(SiO2)ratios are lower in the fine-grained clastic rocks.The w(MnO)/w(TiO2)ratiosare0.02-0.3 inthesilicilith and shales,but the silicilith in Permian Period is4.9.It is indicatedby grochemical analysesof the compositionsof fine-grainedclasticrocks and silicilthrocks that,fromtheSinian Period to Carboniferous Period in southern Hunan,sedi-ments were deposited ina stable intra-continental tectonicsetting;andthat the Permian Periodin southernHunan and Triassic Period in northern Guangdonghada bimodal provennce.Oneof themmaybe of vol-canogenic material.The tectonicsettingis believedto be arelatively active taphrogenic system inthePermianPeriod of southern Hunan and intheTriassic Periodof northernGuangdong.